Exterior spiral staircase adds a dramatic look to any home. Designers and architects normally set the staircase in the middle of the room or slightly off-center. The staircase winds around in a circular pattern to the second floor. The edge length of the steps is variable and depends on the total length of the staircase itself.

Length exterior spiral staircase

If you add a new exterior spiral staircase, you must determine the length of the railing. Measure the space between the outer edges of the stairs to the support pole running through the middle of the staircase, which is the radius. You have to measure between bottoms of the first floor to the bottom of the second floor, which gives you the height of the stairs. Square the height of the steps and add it to the last poll. Find the square of the final number, which gives the length of the stairs.

A rectangular spiral combines a traditional exterior spiral staircase with a circular design. Instead of having the rounded, serpentine shape, the designer uses the rectangles. The finished structure has a more angular or geometric shape. In determining the railing length, you must measure range from a rectangle to the next. Each rectangle or set of steps has its own railing which attaches to the steps. Angled edges put rails flush against each other.